Bar code scanners that use lasers have relatively large depths of field due to the highly collimated nature of the laser. Since the scanning beam which carries the information is so well defined, these bar code scanners are able to use a single element sensor as opposed to an array.
One of the problems with the bar code scanners that use lasers is their relatively high cost, due to the laser diode that is required. A less expensive approach to bar code scanning is provided by using a linear array of light sensitive elements, such as a charge coupled device (CCD) array. These bar code scanners avoid using a laser, but such scanners have in the past had very limited depths of field, with a typical maximum range of approximately one to one and a half inches.
There is a need for a relatively inexpensive bar code scanner that still provides a large depth of field.